Raziya Begum, usually referred to in history as Razia Sultan, was the Sultan of Delhi from 10 November 1236 – 14 October 1240. She was famously the only female ever to rule the Delhi Sultanate.

In 1919 Gandhiji gave a call for a Satyagraha against the Rowlatt Act, passed by the British. The Act restricted the freedom of expression and strengthened police powers. Mahatma Gandhi, Mohammad Ali Jinnah and others strongly opposed this Act. April 6th 1919, was observed as a day opposing the Act.

Earth’s core is the very hot, very dense center of our planet. The ball-shaped core lies beneath the cool, brittle crust and the mostly-solid mantle. The core is found about 2,900 kilometers (1,802 miles) below Earth’s surface, and has a radius of about 3,485 kilometers (2,165 miles).

The ovary is an ovum-producing reproductive organ, found in double pairs in the female as part of the vertebrate female reproductive system. Birds have only one functional ovary (the left), while the other remains vestigial. Ovaries in females are analogous to testes in males, in that they are both gonads and endocrine glands.

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.

Stainless steel is an alloy made by mixing iron with carbon and metals like chromium, nickel and manganese. Stainless steel does not readily corrode, rust or stain with water as ordinary steel does.

The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard pressure. The melting point of ice at 1 atmosphere of pressure is very close to 0 °C (32 °F, 273.16 K); this is also known as the ice point.